In recent years, the computer projector has become the preferred device for audiovisual presentations. A computer projector is a device that projects a picture created from video information received through a peripheral source (e.g., computer, DVD player, or the like). Computer projectors are also known as Digital Projectors or Multimedia Projectors.
During a presentation using a digital projector, the presenter may move in between the projector and the screen, for example to point to an item on the screen. The light that falls on the presenter, especially on the face, irritates the presenter. The presenter may accidentally look at the projector light source. The strong light from the projector may be at best annoying, and at worst harmful to the eye. This problem may occur, for example, during a presentation in a small room with makeshift arrangements.
Well designed auditoriums with screen and projector are properly arranged so that the above described problem is avoided. The projection screen may be positioned high enough above the floor so that the speaker never enters a line-of-sight between the projector and the screen. The speaker/presenter can use a laser light torch to point to images on the screen. This workaround, however, usually can not work in small rooms with low ceilings, which are often used for presentations to small audiences. There is not enough room to locate the projection screen above the height of the presenter, so there is no way to ensure that the presenter does not enter a line-of-sight between the projector and the screen.